Magnetic sensing has numerous advantages compared to other types of sensing. For example, magnetic sensors are generally immune to unclean environments (i.e., environments with dirt, most liquids or environments in which there are various sources of electromagnetic interference) and are relatively simple (especially when commercially-available sensing integrated circuits are used, such as Hall-based sensors and magneto-resistive sensors). Despite having certain advantages, in some applications, noise (often from external magnetic fields not originating within the position measurement system), contributes to the magnetic field sensed at a sensor. When this occurs, sensor measurements are inaccurate. Preventing or reducing the influence of noise typically involves using strong magnets in the sensor, providing magnetic shielding, and positioning magnetic concentrators near the sensor.
Another source of inaccuracy in magnetic sensors is caused by variation of absolute field strength at the sensor. One reason for this variation is a flux change in the magnetic circuit, which can be caused by changes in temperature. Another reason for the variation is variations in the relevant magnetic circuit that are not associated with the position measurement (i.e., gaps between magnetic circuit elements being altered).